Children with attention deficit-hyperactivity disorder showed fewer symptoms after switching to a once-a-day medication made by Shire Pharmaceuticals Group, according to a recent clinical trial.

The study looked at nearly 3,000 children with ADHD. Results were presented Oct. 17 in Miami, Fla. at the annual Children and Adults with Attention-Deficit Hyperactivity Disorder International Conference.

The study found that children who switched to Adderall XR, an extended release version of Shire's Adderall medication, had improved social relationships, scholastic, emotional and physical functioning.

ADHD is the most commonly diagnosed psychiatric disorder among school-aged children. Children with ADHD often are inattentive, impulsive, and hyperactive at levels serious enough to interfere with their academic and social functions.

Doctors involved in the study reported that 60 percent of children were much improved or very much improved after using Adderall XR for six weeks compared to their previous treatment.

Family surveys reported that 60 percent of children using regular Adderall showed improved symptoms. Meanwhile, 86 percent of those who switched from Ritalin and 88 percent of those who switched from Concerta reported improvements.

Shire's U.S. corporate headquarters is in Florence, Ky., where it employs about 150 people. Adderall XR is made in New Jersey.

"This large-scale study is important because it demonstrates Adderall XR can be administered safely and is effective in the real-world setting," said the study's lead investigator, Dr. Paul Ambrosini, a professor of psychiatry at MCP Hahnemann University in Philadelphia.

Few children suffered side effects. The most frequently reported adverse events were headache, insomnia, decreased appetite and abdominal pain.

The U.S. Food and Drug Administration approved Adderall XR in October 2001. It is the long-acting version of Adderall.